1. Technical Field
The present invention relates generally to the field of uses for sophorolipids and more specifically to the field of uses of sophorolipids as antiviral agents.
2. Prior Art
First described in 1961, sophorolipids occur as a mixture of macrolactone and free acid structures that are acetylated to various extents at the primary hydroxyl position of the sophorose ring. Gorin, P. A. et al., Can. J. Chem., vol. 39, p. 846 (1961). Careful examinations have revealed that at least eight structurally different sophorolipids are produced. Davila, A. M. et al., J. Chromatogr., vol. 648, p. 139 (1993). The main component of sophorolipids is 17-hydroxyoctadecanoic acid and its corresponding lactone. Tulloch, A. P. et al., Can. J. Chem., vol. 40, p. 1326 (1962) and Tulloch, A. P. et al., Can J. Chem., vol. 46, p. 3337 (1968).
Work has been carried out to tailor sophorolipid structure during in vivo formation, mainly by the selective feeding of different lipophilic substrates. Zhou, Q. -H., et al., J. Am. Oil Chem. Soc., vol. 72, p. 67 (1995). Also unsaturated C-18 fatty acids of oleic acid may be transferred unchanged into sophorolipids. Rau, U. et al., Biotechnol. Lett., vol. 18, p. 149 (1996). However, while physiological variables during fermentation have provided routes to the variation of sophorolipid composition, this has not led to well-defined pure compounds.
Existing data suggests that glycolipids may be useful in treating very severe immune disorders. For example, glycolipids have been reported to be of interest for in vivo cancer treatment/antitumor cell activity, treatment of autoimmune disorders, in vivo and in vitro antiendotoxic (septic) shock activity, regulation of angiogenesis, and apoptosis induction, all by cytokine activity. See, e.g., U.S. Pat. No. 5,597,573 to Massey, U.S. Pat. No. 5,514,661 to Piljac, U.S. Pat. No. 5,648,343 to Carlson, and the references cited in notes 9-13 of Bisht, K. S. et al., J. Org. Chem., vol. 64, pp. 780-789 (1999).
At the turn of the millennium, the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimated that 34.3 million adults and children were living with HIV/AIDS. More than 18 million had already died of the disease. An estimated 95% of all people living with HIV/AIDS live in developing countries where limited resources and cultural factors make containment of the epidemic especially difficult.
Most HIV infections are transmitted through heterosexual intercourse, and in many areas women are disproportionately affected. About 55% of adults living with HIV/AIDS in sub-Saharan Africa, for example, are women.
The impact of the current level of HIV seroprevalence is enormous in terms of mortality, resource depletion, and human suffering. There is clearly an unmet need for treatment of those already infected. However, there is also a desperate need to prevent further infection.
Efforts to prevent HIV transmission have centered around three approaches: behavioral change (safer sex), the development of a vaccine, and development of a microbicide. In the context of prevention of sexually transmitted diseases (STDs), microbicides are compounds that, when applied topically, protect the body's mucosal surfaces from infection by STD-causing pathogens.
The world's population is increasing at a sustained rate. But population growth is disproportionately high in developing countries with limited resources, those that are especially exposed to infectious diseases such as AIDS. Fertility control and prevention of sexually transmitted diseases are high-priority issues in the public health agenda of developing nations.
Thus, there exists an urgent need to develop new and improved methods for fertility control and prevention of unwanted pregnancies and sexually transmitted infections. It is to the development of sophorolipids for pharmaceutical and industrial purposes, and in particular as microbicides and spermicides or vaginal contraceptives, that the present invention is directed.